Liquid crystal display device

ABSTRACT

A multi-domain alignment liquid crystal display device in which liquid crystal molecules are aligned through a simple process and panel gap is maintained in stable fashion includes a first plate having a thin-film transistor provided at each point of intersection of a scanning line and signal line, a pixel electrode connected to the thin-film transistor and a first orientation layer formed on the pixel electrode and defining a curved surface, and a second plate having RGB color layers, an counterelectrode provided so as to oppose the pixel electrode, and a second orientation layer. A columnar spacer for regulating the panel gap is provided between the two opposing plates, and liquid crystal is sandwiched between the two plates and subjected to multi-domain alignment by the first orientation layer having the curved surface and the columnar spacer.

FIELD OF THE INVENTION

This invention relates to a liquid crystal display device and, moreparticularly, to a liquid crystal display device of the “dividedalignments type”, generally termed as multi-domain alignment(particularly, multi-domain-vertical-alignment) in which, by aligningthe liquid crystal molecules differently in each domain within a singlepixel, the visual-angle characteristics of the respective domainscompensate for each other to provide a wide viewing-anglecharacteristic.

BACKGROUND OF THE INVENTION

Widely known examples of liquid crystal display devices include those ofthe twisted nematic (TN) type and those which employelectrically-controlled birefringence (ECB). However, a problem withthese conventional devices is that since the alignments of the liquidcrystal molecules aligning under application of a voltage are uniformwithin a pixel, tonality differs depending upon the angle of view. Atechnique (multi-domain alignment) through which the directions ofalignment of liquid crystal molecules in a single pixel are made todiffer is available as a method of improving upon the visual-anglecharacteristic. With a liquid crystal device of this kind, thevisual-angle characteristics of the multi-domains compensate for eachother, as a result of which the characteristic is improved.

Multi-domain alignment methods are described in the specifications ofJapanese Patent Kokai Publication JP-A-Nos. 7-318940, 8-292423, 9-80399,9-304757 and 9-21913. These examples of the prior art place surroundingwalls about a pixel and regulate the alignment of the wall surfaces tothereby realize an alignment that is symmetrical with respect to an axisperpendicular to a plate (substrate) at the center of the areasurrounded by the walls. Multi-domain alignment is achieved as a result.Alternatively, protruding and recessed portions having axial symmetrywith respect to the above-mentioned axis of symmetry are formed tocorrespond to the pixel, whereby similar multi-domain alignment isachieved. The art set forth in the specification of Japanese PatentKokai Publication JP-A-8-292423 will be described with reference to FIG.6. FIG. 6 is a sectional view showing one pixel of a conventional liquidcrystal display device. As shown in FIG. 6, walls 23, 24 each comprisinga resist or the like are formed on a plate 1 so as to surround a pixelelectrode 22, and a recessed portion 25 consisting of a resist film isformed between the walls 23 and 24. A counterelectrode 26 is provided ona plate 2 on the opposite side of the device, and a projecting portion27 is formed on the counterelectrode 26. The plates 1, 2 are arranged tooppose each other in such a manner that the recessed and projectingportions 25, 26 will have common axes of symmetry. If the gap betweenthe plates 1, 2 is filled with a mixture of at least liquid crystal anda hardening resin and the liquid crystal and hardening resin are causedto undergo phase separation, a liquid crystal area will develop in sucha manner that the liquid crystal precipitates in the recess or surroundsthe protrusion 27. When this occurs, the liquid crystal molecules in thevicinity of the recess 25 or in the vicinity of the protrusion 27 becomeoriented with axial symmetry, such as in radiating form or in the formof concentric circles, with the axis being perpendicular to the plates.

SUMMARY OF THE DISCLOSURE

In the course of investigations toward the present invention, variousproblems have been encountered. Particularly a number of problems arisewith the example of the prior art described above.

A first problem is that distribution of spacers (spheres etc.) generallyused to maintain the panel gap between the plates is inappropriate. Thereason for this is that the presence of spacers in the pixel areas tendsto provide nuclei resulting in poor liquid crystal alignment, therebygreatly degrading the display characteristic. In contrast, if thespacers would be provided at portions where there are no pixels in orderto avoid the problem of poor alignment, this increases the number ofprocess steps.

A second problem is the requirement of process steps for mixing thehardening resin with the liquid crystal and causing phase separation andcuring after the panel is filled. As a result, process load for formingthe liquid crystal alignment is great.

Accordingly, an object of the present invention is to provide amulti-domain alignment liquid crystal display device in which regulationof the alignment of liquid crystal molecules is carried but through asimple process and panel gap can be maintained in stable fashion.

According to a first aspect of the present invention, there is provideda novel active-matrix liquid crystal display device. The devicecomprises generally first and second transparent insulating platesarranged to oppose each other, the first plate having disposed thereon aplurality of scanning lines and a plurality of signal lines, thin-filmtransistors provided in the vicinity of intersections between thescanning lines and signal lines, and pixel electrodes connected to thethin-film transistors, the second plate having a black matrix providedwith openings at areas that oppose the pixel electrodes, a color layerand counterelectrodes provided so as to oppose the pixel electrodes, aliquid crystal sandwiched between the opposing first and second platesbeing control led by voltage impressed across the pixel electrodes andcounterelectrodes. Further an orientation layer is provided on the pixelelectrodes of the first plate via an insulating film, the orientationlayer being formed into a curved surface and causing molecules of theliquid crystal to become oriented in a direction normal to the curvedsurface of the orientation layer, and columnar spacers for regulatingpanel gap are provided between the two opposing plates. Particularly,each pixel is provided with one spacer.

In the first aspect of present invention, each columnar spacer has anend portion on one side thereof that preferably is disposedapproximately at the center of the orientation layer formed on the firstplate.

In a case where the orientation layer formed on the first plate definesa cavity recessed toward the side of the first plate in a cross sectiontaken along a normal to the plate, the diameter of the columnar spacerbecomes progressively smaller in the direction toward the second plate.

In a case where the orientation layer formed on the first plate definesa protrusion directed toward the side of the second plate in a crosssection taken along a normal to the plate, the diameter of the columnarspacer becomes progressively larger in the direction toward the secondplate.

According to a second aspect of the present invention, there is providedan active-matrix liquid crystal display device generally comprisingfirst and second transparent insulating plates arranged to oppose eachother, the first plate having disposed thereon a plurality of scanninglines and a plurality of signal lines, thin-film transistors provided inthe vicinity of intersections between the scanning lines and signallines, and pixel electrodes connected to the thin-film transistors, thesecond plate having a black matrix provided with openings at areas thatoppose the pixel electrodes, a color layer and counterelectrodesprovided so as to oppose the pixel electrodes, a liquid crystalsandwiched between the opposing first and second plates being controlledby voltage impressed across the pixel electrodes and counterelectrodes.Further, the pixel electrodes on the first plate and an orientationlayer formed on the pixel electrodes define curved surfaces, andcolumnar spacers for regulating panel gap are provided between the twoopposing plates.

In the second aspect of the present invention, the alignment(orientation) layer is formed, e.g., by oblique vapor deposition of SiO,and molecules of the liquid crystal are oriented substantially at rightangles to the plane of the plate.

Each of the columnar spacers has an end portion on one side thereof thatpreferably is disposed approximately at the center of the pixelelectrode formed on the first plate.

In a case where the pixel electrode formed on the first plate defines acavity recessed toward the first plate in a cross section taken along anormal to the plate, the diameter of the columnar spacer becomesprogressively larger (or smaller) in the direction toward the secondplate.

In a case where the pixel electrode formed on the first plate defines aprotrusion directed toward the second plate in a cross section takenalong a normal to the plate, the diameter of the columnar spacer becomesprogressively smaller (or larger) in the direction toward the secondplate.

According to a third aspect, there is provided a multi-domain alignmentactive-matrix liquid crystal display device comprising: first and secondtransparent plates arranged to oppose each other; a liquid crystal beingsandwiched between the first and second plates, and pixel electrodesdisposed on one of the plates and counterelectrodes disposed on theother of the plates and adapted to apply voltage to the liquid crystalacross the pixel electrodes and the counterelectrodes:

wherein an orientation layer is provided on each pixel electrode of oneof said plates via an insulating film,

wherein the orientation layer is formed into a curved or slanted surfaceso as to orient molecules of the liquid crystal in a direction normal tothe curved or slanted surface of said orientation layer, and

wherein columnar spacers are provided between the two opposing platesfor regulating a panel gap between the plates.

The columnar spacers are disposed approximately at a center of theorientation layer on a pixel. The orientation layer defines a cavityrecessed toward one of said plates. The columnar spacer has a side walladapted to assist alignment of the liquid crystal molecules oriented bythe orientation layer to secure multi-domain alignment thereof. Theorientation layer defines a protrusion or recess directed toward one ofsaid plates.

According to a fourth aspect of the present invention, there is provideda multi-domain alignment active-matrix liquid crystal display devicecomprising like components as in the third aspect, provided that anorientation layer is provided on each pixel electrode of one of theplates,

wherein the orientation layer and the pixel electrode are formed into acurved or slanted surface;

wherein columnar spacers are provided between the two opposing platesfor regulating a panel gap between the plates.

According to a fifth aspect, there is provided a multi-domain alignmentactive-matrix liquid crystal display device comprising the components asin the third aspect, provided that an orientation layer is provided atleast on each pixel electrode disposed on one of the plates, and

that columnar spacers are provided between the two opposing plates forregulating a panel gap between the plates.

The columnar spacers have a side wall adapted to pre-align molecules ofthe liquid crystal surrounding each of the columnar spacers centeringthereat. The columnar spacers have a diameter varying along its axis.The columnar spacers have a diameter decreasing or increasing toward oneend thereof.

The side wall is adapted to pre-align molecules of the liquid crystal,e.g., substantially parallel to the side wall. The orientation layer isformed into a curved or slanted surface so as to orient molecules of theliquid crystal in a defined direction normal to the curved or slantedsurface of the orientation layer.

The curved or slanted surface is formed into a recess or protrusion.

Other features and advantages of the present invention will be apparentfrom the following description taken in conjunction with theaccompanying drawings, in which like reference characters designate thesame or similar parts throughout the figures thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing one pixel of a liquid crystal displaydevice according to a first embodiment of the present invention;

FIG. 2 is a plan view showing one pixel of a liquid crystal displaydevice according to the first embodiment of the present invention;

FIG. 3 is a sectional view showing one pixel of another structure of aliquid crystal display device according to the first embodiment of thepresent invention;

FIG. 4 is a sectional view showing one pixel of a liquid crystal displaydevice according to a second embodiment of the present invention;

FIG. 5 is a sectional view showing one pixel of another structure of aliquid crystal display device according to the second embodiment of thepresent invention; and

FIG. 6 is a sectional view showing one pixel of a liquid crystal displaydevice according to the prior art.

FIGS. 7 and 8 schematically illustrate the principle of multi-domainalignment according to the present invention, respectively.

PREFERRED EMBODIMENTS OF THE INVENTION

In a preferred mode of a multi-domain alignment liquid crystal displaydevice, as shown in FIG. 1, a first plate 1 has a thin-film transistorprovided at each point of intersection of a scanning line and signalline, a pixel electrode 8 connected to the thin-film transistor and anorientation layer 10 formed on the pixel electrode and defining a curvedsurface, a second plate 2 has three types of color layers 13 thatcorresponding to the three colors R, G, B, an counterelectrode 14provided so as to oppose the pixel electrode 8, and an orientation layer11, a columnar spacer 12 for regulating the panel gap is providedbetween the two opposing plates 1, 2, and liquid crystal is sandwichedbetween the two plates and subjected to multi-domain alignment by theorientation layer 10 having the curved surface and the columnar spacer.

FIG. 7 schematically illustrates the concept of the columnar spacerdisposed at the center of the pixel electrode between two opposingelectrodes (pixel- and counterelectrodes). By the provision of thecolumnar spacer the molecules of the liquid crystal in a regionsurrounding the spacer are pre-aligned in the direction marked byarrows. The basic (or background) orientation is determined by theorientation layers. In this case the orientation layers opposing eachother orient the molecules of liquid crystal substantially normal to thesurface plane of the orientation layer. The orientation direction of theorientation layer may be controlled by, e.g., oblique depositiontechnique of certain material, e.g., SiO which causes obliqueorientation to the orientation layer. In FIG. 7, the flux linesgenerally represent the basic orientation caused by the orientationlayers.

The columnar spacer may or should have specific alignment properties ofthe liquid crystal molecules, either parallel, perpendicular or atangular relation to the side wall surface. The alignment properties maybe determined and/or further emphasized by the dimensional shape orconfiguration and/or the nature of the material (alignment property,e.g., perpendicular or parallel to the surface thereof).

FIG. 8 schematically represents the basic concept of the combination ofthe curved orientation layer 12 and the columnar spacer. The flux linesrepresent the background orientation caused by the orientation layers 11and 12, in which the orientation i s established perpendicular to thelayer surface. The columnar spacer, being disposed at the center of therecess, further stabilizes the background orientation surrounding thespacer to give multi-domain pre-alignment for one unit area (e.g.,pixel).

If this alignment state is viewed from the top of the layer 11, thereare observed optical multi-domains centered at the spacer for one pixelarea.

This pre-aligned multi-domain formulation of the liquid crystalmolecules provides a uniform gradation or tone of each pixelirrespective of the angle of view, i.e., in a wide angle of view.

Preferred embodiments of the present invention will now be described indetail with reference to the drawings.

First Embodiment

A liquid crystal display device according to a first embodiment of thepresent invention will be described with reference to FIGS. 1 to 3, inwhich FIG. 1 is a sectional view showing one pixel of a liquid crystaldisplay device according to the first embodiment, FIG. 2 a plan view ofthe one pixel and FIG. 3 a sectional view showing one pixel of a liquidcrystal display device in which the shape of the curved surface of anorientation layer differs from that of FIG. 1.

A method of manufacturing the liquid crystal device of the firstembodiment will be described with reference to FIGS. 1 and 2. First, agate electrode 3 and gate wiring 18, which comprise a single layer ormultiple layers of a metal such as Cr or ITO, are formed on thetransparent plate 1 such as glass by a process such as sputtering and aphotoresist step, and a gate insulating film 4 comprising the two layersof silicon oxide and silicon nitride is formed on the gate electrode andgate wiring by a process such as CVD. A semiconductor layer 5 comprisingamorphous silicon (a-Si, n+a-Si) is then formed by a processing (vapordeposition technique) such as CVD and a photoresist step, and a drainelectrode 6, source electrode 7 and drain wiring 19, which comprise asingle layer or multiple layers of a metal such as Cr or ITO, are formedby a process such as sputtering and a photoresist step. The stepsdescribed thus far form the drain wiring, gate wiring and a switchingelement. The wiring layer may extend in a direction substantially inagreement with the direction of a transmission axis of a polarizerprovided on the first or second plate.

Next, the pixel electrode 8 comprising a transparent, electricallyconductive film such as ITO is formed by a process such as sputteringetc. and a photoresist step. A recess is formed on the pixel electrode 8by a transparent insulating film 9. Specifically, acrylic resin orpolyimide resin, for example, is used as a thermoplastic material, aportion having a comparatively large film thickness is formed on thepixel electrode 8 by a photoresist process, and then the oblique (orcurved) surface and bottom of the recess are formed utilizing thethermoplasticity of the material. Next, the orientation layer 10comprising a transparent insulating film which causes liquid crystalmolecules to align perpendicular to the film surface is formed on theinsulating film 9. Specifically, polyimide resin SE-121 (manufactured byNissan Kagaku K. K.) is applied to the insulating film 9 and thepolyimide resin is heated (cured) under conditions that will suppressthe thermoplasticity of the insulating film 9, thereby forming theorientation layer 10.

The columnar spacer 12 comprising an insulating film is formedsubstantially at the center of the recess. The columnar spacer 12preferably is made of a material that will cause the liquid crystalmolecules to align parallel to the surface of the spacer, and it isdesired that the side surface of the spacer 12 be slanted or inclined.The direction of inclination is decided so as to agree with thedirection in which the liquid crystal molecules are caused to slant bythe recess. In this embodiment, it is preferred that the inclination ofthe side surface of the spacer 12 be such that the diameter (crosssection) of the spacer will broaden in the direction toward the plate 1.Specifically, a column with vertical (upright or straight) side walls isformed from photosensitive acrylic resin or polyimide resin by aphotoresist process. Then, when the column is heated for curing, thetemperature is raised gradually to form the inclined surface (sidewall). It is required that this process be performed under conditionsthat will suppress the thermoplasticity of the insulating film 9 so asto finally form the desired inclination.

The structure of the plate 2 on the opposite side of the device will nowbe described. If the device presents a color display, the color layers13 are formed on the transparent plate 2, which consists of glass or thelike. A transparent electrically conductive film and thecounterelectrode 14, which comprises ITO, are formed on the colorlayer(s) 13 as by sputtering. Next, the orientation layer 11 comprisinga transparent insulating film which orient the liquid crystal moleculesto align perpendicular to the film surface is formed on thecounterelectrode 14. Specifically, the orientation layer 11 is formedusing polyimide resin SE-121 (manufactured by Nissan Kagaku K. K.).

Next, the plates (substrate) 1 and 2 with their orientation layersopposing each other are disposed substantially in parallel with a fixedspacing maintained between them by the columnar spacer 12, and the gapbetween them is filled with a liquid crystal material whose dielectricanisotropy is negative. The material used is MLC-6608 (Merck). In thisembodiment, adding a hardening resin to the liquid crystal material isunnecessary. However, hardening resin may be added if desired, as setforth in Japanese Patent Kokai Publication JP-A-8-292423, (the entiredisclosure thereof being incorporated herein by reference.)

Optical films 15, 16 are affixed to the outer-side surfaces of theplates 1 and 2. The optical films 15, 16 each comprise a polarizer or acombination of a polarizer and an optical compensation film. Thepolarizers affixed to the plates are arranged in such a manner that thelight absorption axes thereof are orthogonal to each other.

In the embodiment described above, a recess is formed by the insulatingfilm 9. However, a protrusion may be formed by the insulating film 9, asillustrated in FIG. 3. In this case the columnar spacer 12 is formed onthe plate 2 and it is preferred that the columnar spacer 12 be formed insuch a manner that its side surfaces be inclined in a direction thatnarrows the spacer in the direction toward the plate 1. Other componentsare the same as those shown in FIG. 1.

Though the planar structure of the pixel electrode 8 may be rectangularin general, a circular or oval shape is preferred if matching with therecess or protrusion is taken into consideration. It is also possible toadopt a composite shape such as the combination of rectangular andcircular shapes shown in FIG. 2.

In terms of operation of the present Embodiment the followingexplanation is given. Now referring to FIG. 1, the pixel surface of theplate 1 defines a recess. In the initial state, which is devoid ofapplied voltage, the liquid crystal molecules are caused to orientgenerally perpendicular to the surface of the recess by the orientationlayer 10. Accordingly, since the direction of an electric field producedwhen a potential difference develops across the pixel electrode 8 andcounterelectrode 14 is substantially perpendicular to the surfaces ofthe plates, the direction of orientation of the liquid crystal moleculesin the initial state tilts relative to the direction of the electricfield.

This direction of tilt agrees with the direction of tilt of the liquidcrystal molecules oriented parallel to the surface of the columnarspacer 12. Since the liquid crystal molecules exhibit negativedielectric anisotropy, they tilt in a direction perpendicular to theelectric field when voltage is applied. In other words, the tilt isincreased further in the initial direction of tilt, as indicated by theliquid crystal molecules 17 in FIG. 1. The transmittance of transmittedlight is controlled by the angle of tilt. Since the liquid crystalmolecules in one pixel tilt with the columnar spacer 12 (i.e., the axisthereof) serving as the axis of symmetry, the display characteristics ofthe respective directions of tilt compensate for each other even if theangle of sight (viewing angle) changes. This makes it possible to obtaina display in which there is little change in color at different viewingangles. The same effect can be obtained with the arrangement of FIG. 3as well.

Second Embodiment

A liquid crystal display device according to a second embodiment of thepresent invention will be described with reference to FIGS. 4 and 5, inwhich FIG. 4 is a sectional view showing one pixel of a liquid crystaldisplay device according to the second embodiment, and FIG. 5 is asectional view showing one pixel of a variant liquid crystal displaydevice in which the shape of the curved surface of an orientation layerdiffers from that of FIG. 4.

The second embodiment differs from the first embodiment in that thepixel electrode 8 is provided on the insulating film 9 and basicallydefines the shape of a recess: wiring 20 is an electrically conductivefilm, preferably a transparent film so as not to block transmittedlight, formed by a process such as sputtering and a photoresist step(here, using ITO) so as to electrically communicate the source electrode7 and pixel electrode 8; a film which orients the liquid crystalmolecules perpendicular to the horizontal plane of the plates is adoptedas an orientation layer 21 (and is formed, here, by oblique vapordeposition of SiO); and the direction of inclination of the side surface(wall) of the columnar spacer 12 is such that the cross section of thecolumnar spacer 12 narrows in the direction toward the plate 1.

According to this arrangement, the pixel electrode 8 generally makes upor defines a recess. As a result, the electric field produced atapplication of voltage is not perpendicular to the horizontal plane ofthe plates but is nearly perpendicular to the curved surface of therecess. When the liquid crystal molecules would be orientedperpendicular to the curved surface in the initial state, therefore, asin the foregoing embodiment, the direction of orientation and thedirection of the electric field substantially would coincide and thedirections in which the liquid crystal molecules tilt would occur inrandom fashion, thus causing a faulty display. Accordingly, it isdesired that the liquid crystal molecules be oriented perpendicular tothe plane of the plates in the initial state.

In this arrangement, the direction of tilt of the liquid crystalmolecule 17 differs from that of the first embodiment and, hence, thedirection of inclination of the side surface of columnar spacer 12 alsois changed accordingly. Further, the wiring 20 may be formed through aprocess the same as that used to fabricate the source electrode 7. Insuch case, use of a light-blocking electrically conductive film may becontemplated. However, a decline in transmittance can be suppressed bymaking the direction in which the wiring 20 extends agree with thedirection of the light transmission axis of the polarizer as much aspossible. Furthermore, by achieving electrical communication with thepixel electrode 8 at the bottom of the recess, it is unnecessary toseparately provide an opening to effect such communication. This makesit possible to hold down any increase in the process load.

FIG. 5 illustrates a variant case in which the insulating film 9 is madea protrusion instead of a recess. Similar effects can be obtained withthis arrangement as well. Further, in FIG. 5, the insulating film 9 isprovided with a opening by a photoresist step in order to establishelectrical communication between the source electrode 7 and the pixelelectrode 8. However, depending upon the shape of the insulating film 9,the two electrodes can be communicated directly without forming anopening.

The present invention provides the effects described below.

The first effect is that the direction of alignment of the liquidcrystal molecules can be regulated stably. The reason for this is thatthe columnar spacer is formed at the center of the recess or protrusioncorresponding to a pixel, and the columnar spacer has a surface thatslants in a direction that conforms to the direction in which the liquidcrystal molecules are tilted. Furthermore, the liquid crystal moleculesare oriented parallel to the slanted surface of the columnar spacer inthe initial state. Since only a columnar spacer is present at the pixelportion of the device, faulty orientation or alignment does not readilyoccur.

A second effect is a smaller process load. The reason for this is thatsince the columnar spacer functions as both a column for regulatingorientation of the liquid crystal molecules and a spacer for supporting(or retaining) the panel gap, the column and spacer can be formed by asingle step. In addition, it is unnecessary to mix a hardening resinwith a liquid crystal material in order for alignment of the liquidcrystal to be achieved stably. This makes it possible to dispense withprocesses for phase separation and hardening.

As a result of the effects set forth above, it is possible to obtain,through a comparatively simple process, a liquid crystal display devicehaving a wide viewing in which there is little variance in tonality orgradation of individual pixels observed mainly when the visual angle ischanged.

As many apparently widely different embodiments of the present inventioncan be made without departing from the spirit and scope thereof, it isto be understood that the invention is not limited to the specificembodiments thereof except as defined in the appended claims.

It should be noted that other objects and aspects of the presentinvention will become apparent in the entire disclosure and thatmodifications may be done without departing the gist and scope of thepresent invention as disclosed herein and appended herewith.

Also it should be noted that any combination of the disclosed and/orclaimed elements, matters and/or items may fall under the modificationsaforementioned.

1. A multi-domain alignment active-matrix liquid crystal display devicecomprising first and second transparent insulating plates arranged tooppose each other; said first plate having disposed thereon a pluralityof scanning lines and a plurality of signal lines, thin-film transistorsprovided in the vicinity of intersections between the scanning lines andsignal lines, and pixel electrodes connected to the thin-filmtransistors; said second plate having a black matrix provided withopenings at areas that oppose said pixel electrodes, a color layer andcounterelectrodes provided so as to oppose said pixel electrodes; aliquid crystal being sandwiched between the opposing first and secondplates and being controlled by voltage impressed across said pixelelectrodes and said counterelectrodes; wherein each of said pixelelectrodes on said first plate and an orientation layer formed on saidpixel electrode defines a curved surface, and wherein at least onecolumnar spacer having a diameter varying along its axis is providedbetween the two opposing plates for regulating a panel gap therebetween,said at least one columnar spacer disposed approximately at a center ofa pixel.
 2. The device according to claim 1, wherein said orientationlayer is adapted to orient molecules of the liquid crystal substantiallyat right angles to the planes of said plates.
 3. The device according toclaim 2, wherein said orientation layer is formed by oblique vapordeposition of SiO.
 4. The device according to claim 1, wherein saidpixel electrode formed on said first plate defines a cavity recessedtoward said first plate in a cross section taken along a line normal tosaid first plate; and wherein said columnar spacer has a diameter thatbecomes progressively larger in the direction toward said second plate.5. The device according to claim 2 wherein said pixel electrode formedon said first plate defines a cavity recessed toward said first plate ina cross section taken along a line normal to said first plate; andwherein said columnar spacer has a diameter that becomes progressivelylarger in the direction toward said second plate.
 6. The deviceaccording to claim 1, wherein said pixel electrode formed on said firstplate defines a protrusion directed toward said second plate in a crosssection taken along a line normal to said first plate; and wherein saidcolumnar spacer has a diameter that becomes progressively smaller in thedirection toward said second plate.
 7. The device according to claim 4,wherein a wiring layer is provided beneath said pixel electrode, andsaid wiring layer electrically connects a source or drain electrode ofthe thin-film transistor and said pixel electrode.
 8. The deviceaccording to claim 7, wherein said wiring layer extends in a directionsubstantially in agreement with the direction of a transmission axis ofa polarizer provided on said first or second plate.
 9. The deviceaccording to claim 1, wherein liquid crystal molecules contiguous to thesurface of the columnar spacer are aligned substantially parallel to thesurface of said columnar spacer.
 10. A multi-domain alignmentactive-matrix liquid crystal display device comprising; first and secondtransparent plates arranged to oppose each other; a liquid crystal beingsandwiched between the first and second plates, and pixel electrodesdisposed on one of said plates and counterelectrodes disposed on theother of said plates and adapted to apply voltage to the liquid crystalacross the pixel electrode and the counterelectrodes; wherein anorientation layer is provided on each pixel electrode of one of saidplates, wherein said orientation layer and said pixel electrode areformed into a curved or slanted surface; and wherein at least onecolumnar spacer having a diameter that varies along its axis is providedbetween the two opposing plates for regulating a panel gap between saidplates, and said at least one columnar spacer is disposed approximatelyat a center of a pixel.
 11. The device according to claim 10, whereinsaid orientation layer is adapted to orient the liquid crystal moleculessubstantially at right angles to the planes of said plates.
 12. Thedevice according to claim 10, wherein said pixel electrode defines acavity recessed toward the counterelectrode.
 13. The device according toclaim 12, wherein said columnar spacer has a side wall adapted toprovide multi-domain alignment of molecules of the liquid crystal. 14.The device according to claim 13, wherein said columnar spacer has adiameter increasing toward the counterelectrode opposing the pixelelectrode.
 15. The device according to claim 14, wherein saidorientation layer is adapted to orient molecules of the liquid crystalsubstantially at right angles to the planes of said plates.
 16. Thedevice according to claim 10, wherein said pixel electrode defines acurved or slanted protrusion protruding toward the counterelectrode. 17.The device according to claim 16, wherein said columnar spacer has aside wall adapted to provide multi-domain alignment of the liquidcrystal molecules.
 18. The device according to claim 17, wherein saidcolumnar spacer has a diameter decreasing toward the counterelectrodeopposing the pixel electrode.
 19. The device according to claim 18,wherein said orientation layer is adapted to orient the liquid crystalmolecules substantially at right angles to the planes of said plates.20. A multi-domain alignment active-matrix liquid crystal display devicecomprising; first and second transparent plates arranged to oppose eachother; a liquid crystal being sandwiched between the first and secondplates, and pixel electrodes disposed on one of said plates andcounterelectrodes disposed on the other of said plates and adapted toapply voltage to the liquid crystal across the pixel electrodes and thecounterelectrodes; wherein an orientation layer is provided at least oneach pixel electrode disposed on one of said plates; and wherein atleast one columnar spacer having a side surface that is slanted orinclined is provided between the two opposing plates for regulating apanel gap between said plates, said at least one columnar spacerdisposed approximately at a center of a pixel; wherein said side surfaceof said at least one columnar spacer is adapted to pre-align moleculesof the liquid crystal surrounding each of the columnar spacers centeringthereat; wherein said orientation layer is formed into a curved orslanted surface so as to orient molecules of the liquid crystal in adefined direction normal to the curved or slanted surface of saidorientation layer; and wherein said curved or slanted surface is formedinto a recess.
 21. The device according to claim 20, wherein said curvedor slanted surface is formed into a protrusion.